import re # module d'expressions régulières
chaine = 'x = 120,340, y = 112,450a , point 1'
coord = re.findall(r'[0-9]+[\.|,]*[0-9]+',chaine)
for i in coord:
print i
120,340
112,450
print "x = ",coord[0]
x = 120,340
print "y = ",coord[1]
x = 112,450
# remplacement des virgules par des points dans la chaîne d'origine
xcor = "x = " + re.sub(r',',r'.',coord[0])
ycor = "y = " + re.sub(r',',r'.',coord[1])
un = re.sub(r'x[ ]*=[ ]*\d+[\.|,]*\d+',xcor,chaine)
deux = re.sub(r'y[ ]*=[ ]*\d+[\.|,]*\d+[a-z]*',ycor,un)
print deux
x = 120.340, y = 112.450 , point 1
etc.